Simulating the performance of a Fourier Transform Imaging Spectrometer on NGST.

Due to its simultaneous deep imaging and integral field spectroscopic capability, an Imaging Fourier Transform Spectrograph (IFTS) is ideally suited to the NGST mission, and offers opportunities for tremendous scientific return in many fields of astrophysical inquiry. We describe the operation and quantify the advantages of an IFTS for space applications. We present the expected signal-to-noise performance of an IFTS on NGST and show that its flexible imaging and spectroscopic capabilities can execute efficiently a substantial fraction of the design reference mission. We have built a high-fidelity model that simulates the interferometric data cubes produced by a space-borne IFTS. This artificial data is invaluable because it allows us to visualize directly the data products and performance of an IFTS for comparison with other instruments. We present simulations of deep ( =~ 10(5) s) NGST IFTS observations of rich star fields and the distant Universe. These simulations demonstrate that an IFTS on NGST will be able to spectroscopically classify stars in crowded fields approaching the confusion limit, find and classify distant supernovae on the basis of their spectral signatures alone in single-epoch images, and identify young, forming super star clusters out to redshifts of z =~ 12